The “sword” Christ spoke about is “not at peace” against “arguments/false teachings” which are set against the Truth of God originating from the “rulers/principalities of darkness in the heavenly places” (spiritual warfare).
It’s “not” about fighting with other “men” (flesh & blood) with “weapons if this world” (earthly swords, guns etc).
Here’s the verse which states that literally:
“For though we live in the world, we do not wage war as the world does.
The weapons we fight with are not the weapons of the world. On the contrary, they have divine power to demolish strongholds.
We demolish arguments and every pretension that sets itself up against the knowledge of God, and we take captive every thought to make it obedient to Christ.” (2 Corinthians 10:3 – 5)